| Message ID | 20181213184444.21904-4-geert+renesas@glider.be (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | serial: sh-sci: Fix fallback to PIO on DMA failure | expand |
On Thu, Dec 13, 2018 at 07:44:43PM +0100, Geert Uytterhoeven wrote: > On (H)SCIF, sci_submit_rx() is called in the receive interrupt handler. > Hence if DMA submission fails, the interrupt handler should resume > handling reception using PIO, else no more data is received. > > Make sci_submit_rx() return an error indicator, so the receive interrupt > handler can act appropriately. > > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
On Thu, Dec 13, 2018 at 07:44:43PM +0100, Geert Uytterhoeven wrote: > On (H)SCIF, sci_submit_rx() is called in the receive interrupt handler. > Hence if DMA submission fails, the interrupt handler should resume > handling reception using PIO, else no more data is received. > > Make sci_submit_rx() return an error indicator, so the receive interrupt > handler can act appropriately. > > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c index e353e03ce2602559..8df0fd8245203f8b 100644 --- a/drivers/tty/serial/sh-sci.c +++ b/drivers/tty/serial/sh-sci.c @@ -1331,7 +1331,7 @@ static void sci_tx_dma_release(struct sci_port *s) dma_release_channel(chan); } -static void sci_submit_rx(struct sci_port *s, bool port_lock_held) +static int sci_submit_rx(struct sci_port *s, bool port_lock_held) { struct dma_chan *chan = s->chan_rx; struct uart_port *port = &s->port; @@ -1359,7 +1359,7 @@ static void sci_submit_rx(struct sci_port *s, bool port_lock_held) s->active_rx = s->cookie_rx[0]; dma_async_issue_pending(chan); - return; + return 0; fail: /* Switch to PIO */ @@ -1374,6 +1374,7 @@ static void sci_submit_rx(struct sci_port *s, bool port_lock_held) sci_start_rx(port); if (!port_lock_held) spin_unlock_irqrestore(&port->lock, flags); + return -EAGAIN; } static void work_fn_tx(struct work_struct *work) @@ -1668,8 +1669,10 @@ static irqreturn_t sci_rx_interrupt(int irq, void *ptr) disable_irq_nosync(irq); scr |= SCSCR_RDRQE; } else { + if (sci_submit_rx(s, false) < 0) + goto handle_pio; + scr &= ~SCSCR_RIE; - sci_submit_rx(s, false); } serial_port_out(port, SCSCR, scr); /* Clear current interrupt */ @@ -1681,6 +1684,8 @@ static irqreturn_t sci_rx_interrupt(int irq, void *ptr) return IRQ_HANDLED; } + +handle_pio: #endif if (s->rx_trigger > 1 && s->rx_fifo_timeout > 0) {
On (H)SCIF, sci_submit_rx() is called in the receive interrupt handler. Hence if DMA submission fails, the interrupt handler should resume handling reception using PIO, else no more data is received. Make sci_submit_rx() return an error indicator, so the receive interrupt handler can act appropriately. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> --- v4: - Let sci_submit_rx() return -EAGAIN instead of -1 on failure, - Check for negative error in sci_submit_rx() caller, v3: - Move label handle_pio inside #ifdef to kill defined but not used compiler warning when CONFIG_SERIAL_SH_SCI_DMA=n, - Move the call sci_submit_rx() in sci_rx_interrupt() up, as it may fail, rendering the modification of scr unused, - Split in multiple patches. --- drivers/tty/serial/sh-sci.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)